[SCSI] Simplify error handling

Use wait_for_completion_timeout() instead of using a timer (as
Christoph Hellwig did for aic7xxx).

That lets me eliminate the sym_eh_wait structure; the struct completion,
the old_done pointer and the to_do flag can be folded into the sym_ucmd
(which overrides the scsi_pointer in scsi_cmnd).

The sym_eh_done() function becomes much simpler as the timeout handling
is done in sym_eh_handler() directly.

The host_lock can be unlocked earlier, and I cache the host in
a local variable to make accesses to it quicker.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 22 insertions, 62 deletions

diff --git a/drivers/scsi/sym53c8xx_2/sym_glue.c b/drivers/scsi/sym53c8xx_2/sym_glue.c
index a27dd66b6613..e48409e26e5f 100644
--- a/drivers/scsi/sym53c8xx_2/sym_glue.c
+++ b/drivers/scsi/sym53c8xx_2/sym_glue.c
@@ -137,24 +137,14 @@ static void sym2_setup_params(void)
 static struct scsi_transport_template *sym2_transport_template = NULL;
 
 /*
- *  Used by the eh thread to wait for command completion.
- *  It is allocated on the eh thread stack.
- */
-struct sym_eh_wait {
-        struct completion done;
-        struct timer_list timer;
-        void (*old_done)(struct scsi_cmnd *);
-        int to_do;
-        int timed_out;
-};
-
-/*
  *  Driver private area in the SCSI command structure.
  */
 struct sym_ucmd {               /* Override the SCSI pointer structure */
+        struct completion done;
+        void (*old_done)(struct scsi_cmnd *);
         dma_addr_t data_mapping;
-        u_char  data_mapped;
-        struct sym_eh_wait *eh_wait;
+        int to_do;
+        u_char data_mapped; /* corresponds to data_mapping above */
 };
 
 #define SYM_UCMD_PTR(cmd)  ((struct sym_ucmd *)(&(cmd)->SCp))
@@ -713,55 +703,35 @@ static void sym53c8xx_timer(unsigned long npref)
 #define SYM_EH_DO_WAIT          2
 
 /*
- *  Our general completion handler.
+ *  scsi_done() alias when error recovery is in progress.
  */
-static void __sym_eh_done(struct scsi_cmnd *cmd, int timed_out)
+static void sym_eh_done(struct scsi_cmnd *cmd)
 {
-        struct sym_eh_wait *ep = SYM_UCMD_PTR(cmd)->eh_wait;
-        if (!ep)
-                return;
-
-        /* Try to avoid a race here (not 100% safe) */
-        if (!timed_out) {
-                ep->timed_out = 0;
-                if (ep->to_do == SYM_EH_DO_WAIT && !del_timer(&ep->timer))
-                        return;
-        }
+        struct sym_ucmd *ucmd = SYM_UCMD_PTR(cmd);
+        BUILD_BUG_ON(sizeof(struct scsi_pointer) < sizeof(struct sym_ucmd));
 
-        /* Revert everything */
-        SYM_UCMD_PTR(cmd)->eh_wait = NULL;
-        cmd->scsi_done = ep->old_done;
+        cmd->scsi_done = ucmd->old_done;
 
-        /* Wake up the eh thread if it wants to sleep */
-        if (ep->to_do == SYM_EH_DO_WAIT)
-                complete(&ep->done);
+        if (ucmd->to_do == SYM_EH_DO_WAIT)
+                complete(&ucmd->done);
 }
 
 /*
- *  scsi_done() alias when error recovery is in progress. 
- */
-static void sym_eh_done(struct scsi_cmnd *cmd) { __sym_eh_done(cmd, 0); }
-
-/*
- *  Some timeout handler to avoid waiting too long.
- */
-static void sym_eh_timeout(u_long p) { __sym_eh_done((struct scsi_cmnd *)p, 1); }
-
-/*
  *  Generic method for our eh processing.
  *  The 'op' argument tells what we have to do.
  */
 static int sym_eh_handler(int op, char *opname, struct scsi_cmnd *cmd)
 {
         struct sym_hcb *np = SYM_SOFTC_PTR(cmd);
+        struct sym_ucmd *ucmd = SYM_UCMD_PTR(cmd);
+        struct Scsi_Host *host = cmd->device->host;
         SYM_QUEHEAD *qp;
         int to_do = SYM_EH_DO_IGNORE;
         int sts = -1;
-        struct sym_eh_wait eh, *ep = &eh;
 
         dev_warn(&cmd->device->sdev_gendev, "%s operation started.\n", opname);
 
-        spin_lock_irq(cmd->device->host->host_lock);
+        spin_lock_irq(host->host_lock);
         /* This one is queued in some place -> to wait for completion */
         FOR_EACH_QUEUED_ELEMENT(&np->busy_ccbq, qp) {
                 struct sym_ccb *cp = sym_que_entry(qp, struct sym_ccb, link_ccbq);
@@ -772,10 +742,9 @@ static int sym_eh_handler(int op, char *opname, struct scsi_cmnd *cmd)
         }
 
         if (to_do == SYM_EH_DO_WAIT) {
-                init_completion(&ep->done);
-                ep->old_done = cmd->scsi_done;
+                init_completion(&ucmd->done);
+                ucmd->old_done = cmd->scsi_done;
                 cmd->scsi_done = sym_eh_done;
-                SYM_UCMD_PTR(cmd)->eh_wait = ep;
         }
 
         /* Try to proceed the operation we have been asked for */
@@ -802,28 +771,19 @@ static int sym_eh_handler(int op, char *opname, struct scsi_cmnd *cmd)
 
         /* On error, restore everything and cross fingers :) */
         if (sts) {
-                SYM_UCMD_PTR(cmd)->eh_wait = NULL;
-                cmd->scsi_done = ep->old_done;
+                cmd->scsi_done = ucmd->old_done;
                 to_do = SYM_EH_DO_IGNORE;
         }
 
-        ep->to_do = to_do;
+        ucmd->to_do = to_do;
+        spin_unlock_irq(host->host_lock);
 
-        /* Wait for completion with locks released, as required by kernel */
         if (to_do == SYM_EH_DO_WAIT) {
-                init_timer(&ep->timer);
-                ep->timer.expires = jiffies + (5*HZ);
-                ep->timer.function = sym_eh_timeout;
-                ep->timer.data = (u_long)cmd;
-                ep->timed_out = 1;      /* Be pessimistic for once :) */
-                add_timer(&ep->timer);
-                spin_unlock_irq(np->s.host->host_lock);
-                wait_for_completion(&ep->done);
-                spin_lock_irq(np->s.host->host_lock);
-                if (ep->timed_out)
+                if (!wait_for_completion_timeout(&ucmd->done, 5*HZ)) {
+                        ucmd->to_do = SYM_EH_DO_IGNORE;
                         sts = -2;
+                }
         }
-        spin_unlock_irq(cmd->device->host->host_lock);
         dev_warn(&cmd->device->sdev_gendev, "%s operation %s.\n", opname,
                         sts==0 ? "complete" :sts==-2 ? "timed-out" : "failed");
         return sts ? SCSI_FAILED : SCSI_SUCCESS;